Software-Defined Networking (SDN) can be networking technology that enables a data plane to perform simple traffic forwarding and that enables a central controller to determine a transmitting location and method of traffic by separating a control plane and the data plane and concentrating a control area to a controller. Particularly, by providing various Application Programming Interfaces (APIs) through a northbound API and enabling programming using the various APIs, the controller can perform various traffic controls based on network information. An OpenFlow protocol can be a protocol that supports the SDN to operate and that transfers forwarding information between the controller and a switch and that transfers a state of the switch or traffic information to the controller.
An OpenFlow protocol to be a base of SDN technology has been already standardized in the Open Networking Foundation, and a patent has been applied in relation thereto. However, in standardization and a patent application, a method of transmitting traffic can be discussed and defined. For example, U.S. Patent Laid-Open Publication No. 2011/0261825 in which a patent can be applied to U.S. patent application Ser. No. 13/176,619 by Kiyohisa Ichino (NEC Corporation), and laid-opened with a title of an invention “OpenFlow Communication System and OpenFlow Communication Method” relates to a specification of an OpenFlow protocol. The patent application describes OpenFlow technology and generally discloses operation of OpenFlow and an operation method in a switch to which OpenFlow can be applied.
A method of using an OpenFlow protocol has been discussed. For example, U.S. Patent Laid-Open Publication No. 2012/0300615 in which a patent is applied to U.S. patent application Ser. No. 13/536,838 by four persons (Telefonaktiebolaget LM Ericsson) other than James Kempf and laid-opened with a title of an invention “Implementing EPC in a Cloud Computer with OpenFlow Data Plane” suggests a method of using OpenFlow in a Long Term Evolution (LTE) network. The patent relates to a method of embodying an Evolved Packet Core (EPC) in cloud and describes an example of applying OpenFlow to necessary technology when virtualizing the EPC.
Content caching technology provides contents in which a user equipment (UE) of a mobile communication system requests. An access cache and a core cache provide a content caching function in an eNB and a core. For contents in which a UE requests, it can be first determined whether the same content is stored at an access cache located at an eNB site, and if the same content is stored at an access cache, a corresponding content can be transferred to the UE. In this case, a method of transferring traffic may be changed according to a method of embodying the core cache and the access cache. As a method of transferring traffic, for example, byte caching technique and object caching technique may be used. Such existing content caching technology can exhibit effect only when a content in which the UE requests is stored at an access cache installed at an eNB site. When a corresponding content is not stored at an access cache interworking with an eNB to which the UE can be accessed, but when a corresponding content is stored at an access cache interworking with an adjacent eNB, there can be no method of transferring the content to the UE. Therefore, when a content in which a UE requests is not stored at an access cache interworking with an eNB to which the UE is accessed, but when a corresponding content is stored at an access cache interworking with an adjacent eNB, a method of effectively transferring the content to the UE can be requested.